Pinpoint Test 2: One Low Beam Headlamp Is Inoperative

PINPOINT TEST 2: ONE LOW BEAM HEADLAMP IS INOPERATIVE

Normal Operation

When the smart junction box (SJB) detects the headlight switch in the HEADLAMPS ON position and the multifunction switch in the LOW BEAM position, the SJB provides voltage through circuits (BR/L) to the LH low beam headlamp and (L/G) to the RH low beam headlamp. Ground is supplied through circuit (B/G).

- DTC B2A2E (Right Front Lamp Low Beam Circuit Open) - an on-demand DTC that sets when the SJB detects an open from the RH low beam output circuit.
- DTC B2A2F (Right Front Lamp Low Beam Circuit Short to Ground) - a continuous and on-demand DTC that sets when the SJB detects a short to ground from the RH low beam output circuit.
- DTC B2A30 (Left Front Lamp Low Beam Circuit Open) - an on-demand DTC that sets when the SJB detects an open from the LH low beam output circuit.
- DTC B2A31 (Left Front Lamp Low Beam Circuit Short to Ground) - a continuous and on-demand DTC that sets when the SJB detects a short to ground from the LH low beam output circuit.

Possible Causes
- Fuse
- Wiring, terminals or connectors
- SJB

Diagnostic Procedure

CAUTION:Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE:Due to varying wattage ratings and resulting current draw differences, certain aftermarket headlamp bulbs may cause the SJB to shut down the short circuit protection, resulting in the low beams becoming inoperative. Verify that the bulbs meet Mazda specifications. If the bulbs do not meet Mazda specifications, install the correct bulbs. Run the on-demand self-test (required to clear certain DTCs and reset the SJB). Correct any unresolved DTCs. Clear all DTCs. Test the system for normal operation.
NOTE:Make sure the headlamp bulb is good before continuing diagnostics.

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